Facets

Mtas can produce facets on metadata for Mtas queries. To get this information, in Solr requests, besides the parameter to enable the Mtas query component, the following parameter should be provided.

Parameter Value Obligatory
mtas.facet true yes

Multiple facet results can be produced within the same request. To distinguish them, a unique identifier has to be provided for each of the required document results.

Parameter Value Info Obligatory
mtas.facet.<identifier>.key <string> key used in response no
mtas.facet.<identifier>.field <string> Mtas field yes

Queries

One or multiple queries on the defined Mtas field have to be defined

Parameter Value Info Obligatory
mtas.facet.<identifier>.query.<identifier query>.type <string> query language: cql yes
mtas.facet.<identifier>.query.<identifier query>.value <string> query: cql yes
mtas.facet.<identifier>.query.<identifier query>.prefix <string> default prefix no
mtas.facet.<identifier>.query.<identifier query>.ignore <string> ignore query: cql no
mtas.facet.<identifier>.query.<identifier query>.maximumIgnoreLength <integer> maximum number of succeeding occurrences to ignore no

Variables

The query may contain one or more variables, and the value(s) of these variables have to be defined

Parameter Value Info Obligatory
mtas.facet.<identifier>.query.<identifier query>.variable.<identifier variable>.name <string> name of variable yes
mtas.facet.<identifier>.query.<identifier query>.variable.<identifier variable>.value <string> comma separated list of values yes

Base

One or multiple fields to produce facets over have to be defined

Parameter Value Info Obligatory
mtas.facet.<identifier>.base.<identifier base>.field <string> field to produce facet over yes
mtas.facet.<identifier>.base.<identifier base>.type <string> required type of statistics no
mtas.facet.<identifier>.base.<identifier base>.sort.type <string> sort on term or type of statistics no
mtas.facet.<identifier>.base.<identifier base>.sort.direction <string> sort direction: asc or desc no
mtas.facet.<identifier>.base.<identifier base>.number <double> number of facets no
mtas.facet.<identifier>.base.<identifier base>.minimum <double> minimum number of occurrences span(s) no
mtas.facet.<identifier>.base.<identifier base>.maximum <double> maximum number of occurrences span(s) no

Ranges

Number values can be grouped into ranges by defining a size and optionally a base for these ranges.

Parameter Value Info Obligatory
mtas.facet.<identifier>.base.<identifier base>.range.size <double> size of the range yes
mtas.facet.<identifier>.base.<identifier base>.range.base <double> base for the ranges no

Functions

To compute statistics for values based on the occurrence of one or multiple spans, optionally functions can be added. The parameters for these functions are the number of occurrences $q0, $q1, … for each span and the number of positions $n in a document. Statistics on the value computed for each document in the set are added to the response.

Parameter Value Info Obligatory
mtas.facet.<identifier>.base.<identifier base>.function.<identifier function>.key <string> key used in response no
mtas.facet.<identifier>.base.<identifier base>.function.<identifier function>.expression <string> see functions yes
mtas.facet.<identifier>.base.<identifier base>.function.<identifier function>.type <string> required type of statistics no

The key is added to the response and may be used to distinguish between multiple functions, and should therefore be unique within each specified facet base.

Examples

  1. Basic : basic facet on occurring part of speech
  2. Multiple : multiple facets on occurring part of speech
  3. Variable : facets on occurring part of speech with variable
  4. Range : facet on occurring part of speech with range
  5. Function : facet on occurring part of speech with function

Basic

Example
Facet over year for CQL query [pos="N"].

Request and response
q=*:*&mtas=true&mtas.facet=true&mtas.facet.0.field=test&mtas.facet.0.key=example+-+basic&mtas.facet.0.query.0.type=cql&mtas.facet.0.query.0.value=[pos%3D"N"]&mtas.facet.0.base.0.field=year&mtas.facet.0.base.0.sort.type=sum&mtas.facet.0.base.0.sort.direction=desc&mtas.facet.0.base.0.number=3&rows=0&wt=json&indent=true

"mtas":{
    "facet":[{
        "key":"example - basic",
        "listTotal":257,
        "list":[{
            "mean":380.58187772925766,
            "sum":697226,
            "n":1832,
            "key":"1997"},
          {
            "mean":389.84488636363636,
            "sum":686127,
            "n":1760,
            "key":"1999"},
          {
            "mean":415.17861482381534,
            "sum":683384,
            "n":1646,
            "key":"2002"}]}]}

Multiple

Example
Facet over genre and year for CQL query [pos="N"].

Request and response
q=*:*&mtas=true&mtas.facet=true&mtas.facet.0.field=test&mtas.facet.0.key=example+-+multiple&mtas.facet.0.query.0.type=cql&mtas.facet.0.query.0.value=[pos%3D"N"]&mtas.facet.0.base.0.field=genre&mtas.facet.0.base.0.sort.type=sum&mtas.facet.0.base.0.sort.direction=desc&mtas.facet.0.base.0.number=2&mtas.facet.0.base.1.field=year&mtas.facet.0.base.1.sort.type=sum&mtas.facet.0.base.1.sort.direction=desc&mtas.facet.0.base.1.number=2&rows=0&wt=json&indent=true

"mtas":{
    "facet":[{
        "key":"example - multiple",
        "listTotal":26,
        "list":[{
            "mean":409.7034217657067,
            "sum":65015836,
            "n":158690,
            "listTotal":257,
            "list":{
              "1997":{
                "mean":380.58187772925766,
                "sum":697226,
                "n":1832},
              "1999":{
                "mean":389.84488636363636,
                "sum":686127,
                "n":1760}},
            "key":"jaarboeken"},
          {
            "mean":409.7034217657067,
            "sum":65015836,
            "n":158690,
            "listTotal":257,
            "list":{
              "1997":{
                "mean":380.58187772925766,
                "sum":697226,
                "n":1832},
              "1999":{
                "mean":389.84488636363636,
                "sum":686127,
                "n":1760}},
            "key":"periodieken"}]}]}

Variable

Example
Facet over year for CQL query [pos=$1] with $1 equal to N,ADJ.

Request and response
q=*:*&mtas=true&mtas.facet=true&mtas.facet.0.field=text&mtas.facet.0.key=example+-+variable&mtas.facet.0.query.0.type=cql&mtas.facet.0.query.0.value=[pos%3D$1]&mtas.facet.0.query.0.variable.0.name=1&mtas.facet.0.query.0.variable.0.value=N,ADJ&mtas.facet.0.base.0.field=year&mtas.facet.0.base.0.sort.type=sum&mtas.facet.0.base.0.sort.direction=desc&mtas.facet.0.base.0.number=3&rows=0&wt=json&indent=true

"mtas":{
    "facet":[{
        "key":"example - variable",
        "listTotal":257,
        "list":[{
            "mean":531.8187772925764,
            "sum":974292,
            "n":1832,
            "key":"1997"},
          {
            "mean":545.3232954545455,
            "sum":959769,
            "n":1760,
            "key":"1999"},
          {
            "mean":573.460510328068,
            "sum":943916,
            "n":1646,
            "key":"2002"}]}]}

Range

Example
Facet over year with ranges of size 10 for CQL query [pos="N"].

Request and response
q=*:*&mtas=true&mtas.facet=true&mtas.facet.0.field=test&mtas.facet.0.key=example+-+range&mtas.facet.0.query.0.type=cql&mtas.facet.0.query.0.value=[pos%3D"N"]&mtas.facet.0.base.0.field=year&mtas.facet.0.base.0.sort.type=sum&mtas.facet.0.base.0.sort.direction=desc&mtas.facet.0.base.0.number=3&mtas.facet.0.base.0.range.size=10&mtas.facet.0.base.0.range.base=0&rows=0&wt=json&indent=true

"mtas":{
    "facet":[{
        "key":"example - range",
        "listTotal":29,
        "list":[{
            "mean":369.9619179400794,
            "sum":6149507,
            "n":16622,
            "key":"1990-1999"},
          {
            "mean":559.2636835405855,
            "sum":5711760,
            "n":10213,
            "key":"1900-1909"},
          {
            "mean":482.52500238117915,
            "sum":5066030,
            "n":10499,
            "key":"1910-1919"}]}]}

Function

Example
Facet over year for CQL query [pos="N"] with function.

Request and response
q=*:*&mtas=true&mtas.facet=true&mtas.facet.0.field=test&mtas.facet.0.key=example+-+basic&mtas.facet.0.query.0.type=cql&mtas.facet.0.query.0.value=[pos%3D"N"]&mtas.facet.0.base.0.field=year&mtas.facet.0.base.0.sort.type=sum&mtas.facet.0.base.0.sort.direction=desc&mtas.facet.0.base.0.number=2&mtas.facet.0.base.0.minimum=1&mtas.facet.0.base.0.function.0.key=relative&mtas.facet.0.base.0.function.0.expression=$q0/$n&rows=0&wt=json&indent=true

"mtas":{
    "facet":[{
        "key":"example - basic",
        "listTotal":255,
        "list":[{
            "mean":515.6997041420118,
            "sum":697226,
            "n":1352,
            "functions":{
              "relative":{
                "mean":0.17235837258586809,
                "sum":233.02851973609367,
                "n":1352}},
            "key":"1997"},
          {
            "mean":476.14642609299096,
            "sum":686127,
            "n":1441,
            "functions":{
              "relative":{
                "mean":0.17248794525621,
                "sum":248.55512911419862,
                "n":1441}},
            "key":"1999"}]}]}

Lucene

To produce facets on metadata directly in Lucene, ComponentFacet together with the provided collect method can be used.